1. Field of the Invention
The invention relates to mechanisms for mulching vegetation such as grass as it is being mowed.
2. Description of the Related Art
Conventional mowers typically include a mower housing or deck for enclosing a rotating cutter blade. Discharge chutes have been provided in these conventional housings for allowing grass clippings to be ejected from the housing. The outlet also allows air to be discharged from the housing, thereby allowing the rotating blade to create a vacuum effect that lifts the grass within the housing so that it can be cut properly and evenly. The clippings ejected from the discharge outlet are then blown on top of the mowed grass, or collected by use of a bagging attachment coupled to the discharge outlet. However, it may be desirable to mulch or chop the grass clippings into fine particles and direct these clippings downwardly into the growing grass. This allows the grass clippings to be hidden beneath the top surface of a lawn. In addition, this allows the grass clippings to decompose on the soil where they are of nutritional value to growing vegetation.
In an attempt to meet the need for a mulching mower, mechanisms have been provided that entirely enclose the discharge outlet of the mower housing. The grass clippings are thereby prevented from exiting the housing and are re-cut by the mower blade. However, since these mowers totally block the discharge of air through the outlet, the circulation of air is reduced. Therefore, the vacuum effect is reduced when the discharge is blocked, and the grass is not lifted properly for cutting by the blade.
Also, many prior art mulching mowers having enclosed discharge outlets tend to plug up with grass clippings during mowing operations in heavy or long vegetation. Since there is no outlet for the clippings, they build up within the housing. The clippings tend to wad together and fall out of the housing in unsightly clumps when heavy or long grass is mowed. These mowers tend to deposit grass along the sides of the housing, thereby creating an unsightly "windrowing" of clippings. Also, the relatively small vacuum effect created by the blade in a housing having an enclosed discharge outlet results in a low quality of cut during operation in heavy or long grass.
Other prior art mulching mechanisms provide a plate for covering the discharge outlet of the mower deck, and have slots or other openings formed therein. The slots are provided for allowing air to exit the housing to enhance the vacuum effect within the housing while blocking clippings from exiting the housing. However, prior art mulch plates tend to quickly clog with grass clippings during operation, and therefore tend to act as a solid plate that totally covers the outlet. Therefore, slotted mulch plates that quickly become clogged with clippings have disadvantages similar to those associated with mower decks having totally enclosed outlets.
Other prior art mulching mechanisms provide deflectors and/or plates within the housing for deflecting the clippings forwardly, downwardly and/or inwardly toward the center support for the blade. However, these mechanisms may not provide an assured direction to the deflected grass, and may not therefore always move the clippings into the blade for re-cutting. Typically, prior art mowers having deflector surfaces also have enclosed discharge openings and may therefore create the aforementioned problems of clogging, clumping and windrowing associated with totally blocked discharge openings.
Therefore, it would be desirable to provide a mulching mower that channels a large portion of the circulating air which carries the grass clippings inwardly and downwardly toward the mower blade. It would be desirable for such a mower to maintain an enhanced lifting effect on the uncut grass. It would also be desirable to provide such a mower with an overflow feature such that operation in areas of dense vegetation does not cause the housing to become clogged with clippings, or clippings to be deposited on the ground in clumps or windrows.